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What Is Encephalitis?

Encephalitis is a rare but serious condition that causes inflammation (swelling) of the brain. It is usually caused by a viral infection. Encephalitis affects approximately five to eight people per 100,000 annually. Herpes simplex virus (HSV) encephalitis is the most common viral encephalitis.

What Is The Difference Between Meningitis And Encephalitis?

Encephalitis and meningitis are not the same. Meningitis is an inflammation of the lining that covers the brain and spinal cord (the meninges). It is usually caused by a bacterial or viral infection. Sometimes you can have both encephalitis and meningitis at the same time. This is called meningoencephalitis.

What Causes Encephalitis?

Examples of viral infections that can cause encephalitis include:

  • The virus that causes cold sores and genital herpes (herpes simplex virus)
  • The chickenpox virus (varicella-zoster virus)
  • The mumps virus
  • The measles virus
  • Flu viruses

Elsewhere in the world, other viruses can cause encephalitis after bites by insects such as mosquitoes (Japanese encephalitis virus).

Sometimes encephalitis can develop if your immune system tries to fight off a virus and, at the same time, attacks the nerves in your brain in error. This is known as post-infectious or autoimmune encephalitis.

Very rarely, infection with germs (bacteria, fungi and parasites) can cause encephalitis.

What Are The Symptoms Of Encephalitis?

The symptoms of encephalitis can range from mild to severe. Infants and young children show different symptoms:



Infants and Young Children

  • Fever
  • Headache
  • Vomiting
  • Stiff Neck
  • Lethargy (Exhaustion)


  • Very High Fever (39.5?C or Higher)
  • Confusion
  • Drowsiness
  • Hallucinations
  • Slower Movements
  • Coma
  • Seizures
  • Irritability
  • Sensitivity to Light
  • Unconsciousness
  • Vomiting
  • Bulging Fontanel (Soft Spot in the Scalp)
  • Constant Crying
  • Body Stiffness
  • Poor Appetite


How Is Encephalitis Diagnosed?

  1. Spinal Tap or Lumbar Puncture: A sample of spinal fluid testing for infection.
  2. Brain Imaging with CT scan or MRI: To detect changes in brain structure. They can rule out other possible brain disease, such as a tumor or stroke.
  3. Electroencephalograph (EEG): An EEG uses electrodes (small metal discs with wires) attached to the scalp to record brain activity.  It can show abnormal brainwaves that occur if you have encephalitis.
  4. Other Tests: These can include blood tests, urine tests and swab tests (for example, if you have a blistering skin rash). They can help to identify causes of the encephalitis.

What Is The Treatment For Encephalitis?

Any child with suspected encephalitis needs to be admitted to hospital urgently. Antiviral medication, most commonly used if encephalitis is suspected is a drug named Acyclovir. This is particularly effective in treating encephalitis caused by herpes simplex virus. Treatment with Acyclovir is started straightaway without waiting for confirmation from test results as the medicine needs to be started quickly to be most effective.

Antibiotics may also be given initially. This is because, without test results, it may be difficult to tell the difference between encephalitis and meningitis caused by germs (bacteria).

Other treatments for encephalitis are what doctors call ‘supportive’ treatments to help the body to rest and try to fight the infection or inflammation of the brain. It can include:

  • Rest
  • Pain killers
  • Corticosteroids (to reduce brain inflammation)
  • Mechanical ventilation (to help with breathing)
  • Anticonvulsants (to prevent or stop seizures)
  • Sedatives (for restlessness, aggressiveness, and irritability)
  • Fluids (sometimes through an intravenous line (IV))

If your child has encephalitis, he/she needs close monitoring and nursing. And if the infection is severe, they need to be admitted to an intensive care unit.

What Are The Complications And Outlook (Prognosis)?

Encephalitis can affect different children in different ways. Some children recover from encephalitis and have few, or no, long-term problems. However, in many children, encephalitis is a serious condition and can be life-threatening. Also, after encephalitis, it is common for children to be left with some permanent brain damage. The extent and severity of brain damage can vary greatly.

This brain damage can lead to various problems including:

  • Problems with balance, co-ordination and dexterity
  • Speech problems
  • Weakness and problems with movement
  • Swallowing problems
  • Fits (seizures)
  • Chronic headache
  • Personality changes
  • Memory problems
  • Behavioural problems
  • Mood problems, anxiety and depression
  • Difficulty concentrating

Depending on the type and severity of encephalitis, it may be necessary to receive additional therapy, including:

  • Physiotherapy: to improve strength, coordination, balance, and flexibility
  • Occupational therapy: to help redevelop everyday skills
  • Speech therapy: to help relearn muscle control needed for talking
  • Psychotherapy: to help with coping strategies, mood disorders, or personality changes

Some children who are severely affected with encephalitis need continuous nursing care, as they are no longer able to look after themselves.

Can Encephalitis Be Prevented?

Encephalitis isn’t always preventable, but you can lower your child’s risk by:

  1. Immunisation Programmes in the world against common childhood illnessessuch as measles, mumps and rubella have helped dramatically to reduce the numbers of people who develop encephalitis.
  1. Immunisation Is Also Available Against Viruses That Can Cause Encephalitis in other countries, such as Japanese encephalitis and tick-borne encephalitis caused by insect bites.


  1. Encephalitis Society.(30 October 2014). 
  2. Encephalitis- Causes – NHS Choices.( 16 December 2014)



Last Reviewed : 17 October 2016
Writer : Dr. Sumitha Murugesu
Accreditor   Dr. Khoo Teik Beng